Body fluid suction device indicators

ABSTRACT

A medical suction device is disclosed which includes a vacuum indicator flag. This flag is made up of a flexible tube capped with a plug. The rigidity of the walls of the tube is chosen such that the walls collapse when the pressure inside the tube falls below a predetermined value, thereby allowing the flag to droop. In addition the rigidity of the tube serves to hold the flag upright when the pressure inside the tube rises above a second predetermined value. Thus the state of the flag (upright or drooped) provides a remote indication of the pressure being developed by the suction device. In addition, the suction device uses a constant force coiled ribbon spring to provide substantially constant suction as the suction device is filled. Furthermore, the suction device includes a plurality of separately valved drainage receptacles which can be folded and stored compactly against the drainage device. By sequentially filling each of these receptacles and then removing the respective receptacle from the drainage device only after the respective isolation valve has been closed, relatively large volumes can be drained without opening the suction device to atmosphere.

BACKGROUND OF THE INVENTION

The present invention relates to an improved suction device used tocollect body fluids.

Modern medical practice commonly uses suction devices to improvedrainage of fluids from the body of a patient. For example, suctiondevices are routinely used to speed wound drainage following surgery.One type of wound suction device includes a portable, relatively smallsuction chamber which is coupled to a source of body fluids. Typically,such chambers are repeatedly charged with a vacuum, filled with bodyfluids, and then drained during the course of a single drainagetreatment. U.S. Pat. Nos. 3,889,677 and 3,779,243 disclose two suchportable suction devices.

A potential drawback of many such devices is that it is often difficultto determine from a distance whether the device is developing propersuction. Generally, a portable suction device of the type describedabove will lose suction when it becomes filled. Unless the loss ofsuction is promptly noticed and the chamber is emptied to restoresuction, proper drainage may be interrupted.

Another potential drawback of many prior art devices relates to theamount of suction developed at various stages in the use of the suctiondevice. Preferably, a suction device should develop a uniform suctionthroughout its fill cycle, rather than a higher suction when the deviceis empty and a progressively lower suction as the device fills.

A third drawback of the prior art relates to the contamination ofsuction devices in use. As explained above, it is customary to fill andempty a suction device repeatedly during a single drainage treatment.Conventional drainage devices must be opened to be drained, and they cantherefore become contaminated during use. This contamination can thenspread to the patient when drainage is resumed.

SUMMARY OF THE INVENTION

The present invention is directed to an improved suction device whichovercomes these and other disadvantages of the prior art.

According to a first aspect of the invention, a suction device includesa vacuum indicator signal or flag. This flag includes a flexible tube influid communication with the interior of the suction device. Therigidity of the tube is chosen such that when a high vacuum is presentthe walls of the tube collapse, thereby reducing the resistance of thetube to lateral bending. Conversely, when a low vacuum or no vacuum ispresent the tube returns to its rest state, in which the tube exhibitsincreased resistance to lateral bending. In the preferred embodiment, amass is attached to the end of the tube such that the tube stands erectwhen low vacuum is present and the tube droops under the weight of themass when high vacuum is present. By adjusting the rigidity of the tubeand the weight of the mass properly, the tube can be made to droop atthe desired vacuum.

This first aspect of the invention provides a simple, direct, reliableand inexpensive indication of the vacuum contained in the suctiondevice. Furthermore, the tube can readily be made of a size and colorsuch that the flag can be seen from a considerable distance to allowremote inspection of the state of the suction device.

According to a second feature of the invention, a suction deviceincludes a substantially constant force spring, such as a negator springfor example, arranged to expand the volume of the suction device suchthat a substantially constant vacuum is produced as the device fills.Constant force springs of the type disclosed below are reliable andcompact. They can be used to create a relatively simple suction devicewhich utilizes any one of several types of vacuum containers.

According to a third aspect of the invention, a suction device isprovided with a plurality of drainage receptacles, each of which isconnected to the suction device by means of an independently operableisolation valve such that any one of the receptacles can selectively beplaced in fluid communication with the suction device. Preferably, eachof the receptacles is collapsible for compact storage adjacent thesuction device.

This third aspect of the invention provides a closed system suctiondevice having a total drainage capacity which can be much greater thanthat of the suction device itself. The suction device can be repeatedlyfilled and drained into the receptacles, and individual receptacles canbe removed from the suction device after they have been filled and therespective isolation valves closed, all without ever opening the suctionsystem to atmosphere. In this way, contamination of the suction deviceand concomitant infection of the patient are reduced.

The invention itself, together with further objects and attendantadvantages, will best be understood by reference to the followingdetailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view in partial cutaway of a first preferredembodiment of the suction device of the present invention.

FIG. 2 is a perspective view of an accessory for use with the embodimentof FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1.

FIG. 4 is a cross-sectional view of a second preferred embodiment of thesuction device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, FIGS. 1-3 represent a first preferredembodiment of the suction device of this invention. As shown in FIGS. 1and 3, this first preferred embodiment includes a frame 10 which servesas a rigid mount for a shaft 12 and a cylinder 20. Spaced parallelsupport bars 14 are interposed between and rigidly secured to the frame10 and the cylinder 20 in order to securely hold the cylinder 20 inplace.

A piston 30 having a moveable wall portion is slidably mounted insidethe cylinder 20. This piston 30 is provided with two spaced seals 32which form a vacuum seal between the piston 30 and the cylinder 20.Preferably, these seals 32 are formed of a relatively soft sealingmaterial such as silicone rubber, for example. A pair of constant force,coiled ribbon springs 40 are mounted to a sleeve 42 which is rotatablymounted on the shaft 12. These springs, which are commonly known asnegator springs, provide a substantially constant force as they arewound or unwound from the sleeve 42. One end of each of the springs 40is connected to the piston 30 by means of a flexible coupling 50.

The end of the cylinder 20 nearest the shaft 12 is provided with acollar 60. This collar 60 provides a stop 62 which serves to confine thepiston 30 within the cylinder 20. A tubular sleeve 70 of a flexible,elastomeric material is secured between the collar 60 and the piston 30.This sleeve 70 serves to protect the inner walls 22 of the cylinder 20from exposure to atmosphere and contamination as the piston 30 moveswithin the cylinder 20. In addition, the dual seals 32 provide anadditional barrier which serves to maintain the sterility of the suctionchamber 24 defined by the cylinder 20 and the piston 30.

The piston 30 has a constant area surface which is drawn toward theshaft 12 by a substantially constant force provided by the springs 40.Therefore the suction device of FIGS. 1 and 3 provides a substantiallyconstant suction as the piston moves within the cylinder 20.

A conduit 80 is connected to the suction chamber 24 by means of a bore84. A check valve 82 is interposed in the conduit 80 to insure thatfluids do not pass from the suction chamber 24 out the conduit 80. Inuse, the conduit 80 is connected to a source of body fluids, such as awound catheter for example. The conduit 80 thus serves to conduct bodyfluids from a patient into the suction chamber 24.

In addition, an indicator flag 90 is provided. This flag 90 comprises ahollow flexible tube 92, the interior of which is in fluid communicationwith the suction chamber 24 by means of a bore 96. The distal end of thetube 92 is provided with a plug 94. As will be explained below, theweight of this plug 94 can be important in the functioning of theindicator flag 90.

In addition, a drainage bore 100 is provided which interconnects thesuction chamber 24 with a manifold 102. A plurality of conduits 104 areconnected to the manifold 102, and each of these conduits 104 isprovided with a separately operable isolation valve 106. In addition,each of the conduits 104 is coupled to an individual receptacle 108.Preferably, these receptacles 108 are flexible plastic receptacles whichcan be folded into a compact volume and stored against the cylinder 20when not in use. FIGS. 1 and 3 show one of the receptacles 108a in itsunfolded state. Each of the isolation valves 106 can be operatedindependently of the others, and each valve 106 is movable between aclosed state, in which the manifold 102 is isolated from the respectivereceptacle 108, and an open state, in which the respective receptacle108 and the manifold 102 are interconnected.

Preferably the suction chamber 24, the indicator flag 90, and themanifold 102 with attached receptacles 108 form a closed, sterile unit.As explained above, the sleeve 70 and the seals 32 contribute tomaintaining the sterility of this unit. In this preferred embodiment,the cylinder 20 is made of a rigid plastic such as the plastics commonlyused to form plastic syringes. In addition the tube 92 of the indicatorflag 90 is formed of a silicone rubber which defines a flexible wallhaving a resilience sufficient to hold the tube 92 and the plug 94upright, as shown in FIG. 3, when the pressure inside the suctionchamber 24 is greater than a first predetermined amount. However, whenthe pressure within the suction chamber 24 is less than a secondpredetermined amount, the atmospheric pressure pushes the walls of thetube 92 together, thereby reducing the lateral rigidity of the tube 92.In these circumstances the weight of the plug 94 acts to pull the tube92 downward, away from its erect position of FIG. 3. FIG. 1 provides aperspective view of the indicator flag 90 as it appears when thepressure in the suction chamber 24 is less than the second predeterminedamount.

Preferably, the springs 40 are chosen such that the suction developedwithin the suction chamber 24 is in the range 75-90 mm Hg belowatmospheric pressure. Associated Springs, Barnes Group, Inc., BristolConnecticut is one supplier for the constant face springs 40. In thispreferred embodiment, the indicator flag 90 assumes the uprightposition, as shown in FIG. 3, when the suction in the chamber 24 is lessthan about 20 mm Hg below atmospheric pressure and the flag 90 assumesthe position of FIG. 1 when the suction in the chamber 24 is greaterthan about 40 mm Hg below atmospheric pressure. Between 20 and 40 mm Hg,the indicator flag 90 assumes intermediate positions, thereby providingadditional information as to the degree of suction in the chamber 24. Itcan thus be seen from the above that the indicating device is designedfor operation at subatmospheric pressures.

In this preferred embodiment the flag 90 comprises a tube made ofsilicone rubber having an outer diameter of 5/16 inch, a wall thicknessof 1/32 inch, a length of about 43/4 inches, and a hardness of 75durometer Shore A scale. Preferably the plug 94 has a mass of betweenone and one and one-half grams. Of course, the rigidity of the walls ofthe tube 92, the composition of the tube 92, and the weight of the plug94 can be readily adjusted to cause the flag 90 to change state at othernegative pressures, as desired.

FIG. 2 shows a perspective view of a hand tool 110 which is used inoperating the suction device of FIGS. 1 and 3. This hand tool 110includes an opening 112, a cut-out region 118, an end section 114, and ahandle 116.

Referring now particularly to FIG. 3, the operation of this firstpreferred embodiment can now be described. To prepare the suction deviceof FIG. 3 for use, the hand tool 110 is placed with the end section 114against the piston 30. The handle 116 is then grasped and force ismanually exerted to extend the springs 40 and to push the piston 30against the end 26 of the cylinder 20. Once the spring 40 is fullyextended, the hand tool 110 can be locked in position by placing the tab16 within the opening 112 of the hand tool 110. The conduit 80 can thenbe connected to a wound catheter or another source of body fluids to bedrained under suction. In this situation, when there is relatively highpressure within the suction chamber 24, the indicator flag 90 standsupright as shown in FIG. 3.

In order to begin drainage, each of the three isolation valves 106 isclosed, the conduit 80 is connected to a source of body fluids, and thehand tool 110 is removed. The springs 40 then exert a substantiallyconstant force tending to withdraw the piston 30 away from the end 26 ofthe cylinder 20. This creates a substantially constant suction tendingto draw body fluids through the conduit 80 into the suction chamber 24.FIG. 1 shows a perspective view of this embodiment of the invention inuse. Note that the indicator flag 90 has collapsed, thereby indicatingthe presence of adequately low pressure within the suction chamber 24.

Once the piston 30 has withdrawn to the maximum extent possible againstthe stop 62, the pressure inside the suction chamber 24 will rise, andthe indicator flag 90 will return to the upright position shown in FIG.3. In order to drain the suction chamber 24 and to prepare it forfurther use, a selected one of the isolation valves 106 is opened, andthe hand tool 110 is then used to push the piston 30 towards the end 26of the cylinder 20. This forces body fluids out of the suction chamber24 into the selected receptacle 108. The check valve 82 prevents drainedfluids from being pushed back up the conduit 80 into the patient. Oncethe piston 30 has been returned to its extended position against the end26 of the cylinder 20, the drainage procedure can be resumed.Preferably, all of the isolation valves 106 are closed while suction isapplied to the conduit 80 to prevent body fluids from being drawn backinto the suction chamber 24 from the receptacle 108.

It will be understood that the total drainage capacity of the embodimentof FIGS. 1 and 3 can be much greater than the capacity of the suctionchamber 24. For example, the suction chamber 24 can be provided with atotal capacity of two hundred of four hundred or six hundred millilitersand each of the receptacles 108 can be provided with a total capacity ofone liter. Since the receptacles 108 can be folded into a compact volumefor storage, the total size of the embodiment of FIGS. 1 and 3 is small.Nevertheless, a large volume of body fluids can be drained under suctionwithout ever opening the suction chamber 24 to atmosphere.

When a receptacle 108 has been filled in the manner described above, therespective isolation valve 106 can be closed, and then the entirereceptacle 108 can be severed from the suction device for disposal,while leaving the respective isolation valve 106 connected to thesuction device such that the suction chamber 24 is never opened toatmosphere. Drainage can then continue by opening another isolationvalve 106 and unfolding the respective receptacle 108 to receive bodyfluids. Thus, a high volume suction device is provided which isrelatively low in bulk and yet which can be used without opening thesuction chamber to atmosphere. In this way contamination of the suctionchamber 24 and concomitant infection of the patient can be reduced.

Turning now to FIG. 4, a second preferred embodiment 200 of the presentinvention includes a frame 210 which serves as a rigid mount for a shaft212 and a pair of spaced parallel support bars (not shown, but similarto the support bars 14 of FIG. 1). A cylinder 220 is rigidly mounted tothe support bars 214 and thereby to the frame 210. A pair of smallerconcentric cylinders 222,224 are slidably mounted within the cylinder220. Each of the cylinders 220,222 defines an annular lip 226, and eachof the cylinders 222,224 defines a mating flange 228. The lips 226 andthe flanges 228 cooperate to form stops to define the maximum extensionof the cylinders 222,224 within the cylinder 220. A flexible plasticcover 230 is bonded between cylinder 220 and cylinder 224 to seal thesuction chamber 232 defined by the interior of the cylinders220,222,224. A pair of constant force springs 240 are coiled about asleeve 242 which is rotatably mounted on the shaft 212. These springs240 are mounted by means of a flexible coupling 252 to the end of theinnermost cylinder 224. As in the first preferred embodiment of FIGS. 1and 3, the spring 240 provides a substantially constant force in thedirection of the shaft 212.

As in the first preferred embodiment, this second preferred embodiment200 includes a conduit 280 which is coupled by means of a check valve282 and a bore 284 to the suction chamber 232. In addition, an indicatorflag 290 comprising a flexible tube 292 and a plug or mass 294 is influid connection with the suction chamber 232 by means of a bore 296.Moreover, a bore 300 serves to connect a manifold 302 with the suctionchamber 232, and this manifold 302 is connected by a plurality ofconduits 304 with respective isolation valves 306 and receptacles 308.

In addition, a tension member 310, which in this preferred embodiment ismade up of a monofilament nylon cord, is attached to the innermostcylinder 224 inside the suction chamber 232. This tension member 310extends through a seal 312 to the exterior of the suction device. Thedistal end of the tension member 310 is provided with a handle 314, anda V-shaped groove 316 is defined in a rib secured to the frame 210.

This second preferred embodiment is prepared for use by manually pullingthe handle 314 of the tension member 310 to move the inner cylinder 224towards the indicator flag 290, and thereby to extend the springs 240.Once the volume of the suction chamber 232 has been reduced to thesmallest volume possible, the tension member 310 can be wedged intoposition in the V-shaped groove 316 in order to maintain the springs 240in the extended position. Suction can be applied to the conduit 280 bymerely releasing the tension member 310 from the V-shaped groove 316,thereby allowing the springs 240 to act to expand the volume of thesuction chamber 232. As before, the indicator flag 290 provides a remotevisual indication of the pressure inside the suction chamber 232. Ifdesired, a protective cover can be installed around the exterior portionof the tension member 310 in order to reduce the chances ofcontamination of the suction chamber 232. The seal 312 preferablyprovides a wiping action to reduce contamination which may enter thesuction chamber 232 on the tension member 310.

From the foregoing, it should be apparent that an improved suctiondevice has been disclosed which provides a number of importantadvantages. First, this suction device includes a simple, reliableindicator of the suction being developed by the suction device. In thepreferred embodiment this indicator is a tubular flag having a length ofthree or more inches which droops markedly when the suction is withinthe desired range. This visual indicator can easily be monitored acrossa room, and it therefore facilitates proper monitoring of the suctiondevice.

Second, the embodiments described above utilize a simple and reliableconstant force, coiled ribbon spring to provide substantially constantsuction throughout the filling of the suction chamber. Constant suctionprovides the important advantage that the level of suction can be chosenand maintained at its optimum level in order to promote drainageoptimally.

A third important advantage of the embodiments described above is thatthey allow closed system suction drainage. As explained above, arelatively small capacity suction chamber can be used in combinationwith a number of separately valved drainage receptacles. The suctiondevice can be repeatedly filled and emptied into the variousreceptacles, which can be separated from the suction device as theybecome filled. Because the entire suction device is a single, sealed,sterile unit, there is no need to attach receptacles, or to reattachfresh receptacles to the drainage device. By avoiding this intermittentopening of portions of the drainage device to atmosphere, contaminationof the drainage device and therefore infection of the patient arereduced.

Of course, it should be understood that various changes andmodifications to the preferred embodiments described above will beapparent to those skilled in the art. For example, coiled constant forcesprings of the type which exert a pushing rather than a pulling forcecan be used to provide a constant suction device of the type describedabove. In addition, it may not be necessary to utilize a mass such asthe plug 94 in all embodiments to obtain the desired droopingcharacteristics of the indicator flag 90. Furthermore, the size andproportion of the embodiments described above can be varied as needed tosuit individual applications. Such changes and modifications do notdepart from the spirit and scope of the present invention. It istherefore intended that the following claims be interpreted to cover allsuch changes and modifications.

We claim:
 1. A suction device for receiving body fluidscomprising:container means including a constant force moveable wallmeans for defining a suction chamber adapted to maintain asubatmospheric pressure and to receive body fluids: a vacuum indicatorcomprising a flexible tube which is closed at one end by a preselectedmass, said tube movable between a rest state, in which the interiorvolume of the tube has a first value, and a collapsed state, in whichthe interior volume of the tube is substantially less than the firstvalue; means for mounting the tube to the container means such that theinterior volume of the tube is in fluid communication with the suctionchamber; the flexibility of said tube being chosen such that the tubecollapses to the collapsed state when a subatmospheric pressure lessthan a first predetermined value is induced in the suction chamber, andthe tube returns to the rest state when the pressure in the containermeans rises to a value greater than a second predetermined value,greater than the first predetermined value, such that the tube providesa visual indication of the pressure in the suction chamber.
 2. Theinvention of claim 1 wherein the closed end of the tube projects awayfrom the container means when the tube is in the rest state and whereinthe flag further comprises the mass secured to the closed end of thetube, the weight of said mass being chosen such that the tube is erectwhen the tube is in the rest state and the tube is deflected by the masswhen the tube is in the collapsed state.
 3. The invention of claim 2wherein the tube is formed of an elastomeric material.
 4. The inventionof claim 2 wherein the mass comprises a stopper which fits in the tubeto seal the closed end of the tube.
 5. The invention of claim 1 whereinthe transition between the rest state and the collapsed state is gradualsuch that the flag provides a visual indication of the pressure betweenthe first and second predetermined values.
 6. A suction device forreceiving body fluids comprising:container means including a constantforce moveable wall means for defining a suction chamber adapted tomaintain a subatmospheric pressure and to receive body fluids; means forconnecting the suction chamber to a source of body fluids; a flexibleplastic tube having an open end and a closed end that is closed by apreselected mass; means for connecting the open end of the tube to thecontainer means such that the interior of the tube is in fluidcommunication with the suction chamber and the tube extends away fromthe container means; and a weight secured to the tube at a point remotefrom the open end; the rigidity of the tube and the size of the weightchosen being such that the tube stands erect when a pressure greaterthan a first predetermined amount is induced inside the suction chamberand the tube collapses and droops when a subatmospheric pressure lessthan a second predetermined amount is induced inside the suctionchamber, thereby providing a clear visual indication of the pressureinside the suction chamber.
 7. A suction device for receiving bodyfluids comprising:container means including a constant force moveablewall means for defining a suction chamber adapted to maintain asubatmospheric pressure and to receive body fluids; a flexible plastictube having an open end and a closed end that is closed by a preselectedmass; means for connecting the open end of the tube to the containermeans such that the interior of the tube is in fluid communication withthe suction chamber and the tube extends away from the container means;and a weight secured to the tube at a point remote from the open end;the rigidity of the tube and the size of the weight chosen such that thetube stands erect when a pressure greater than a first predeterminedamount is induced inside the suction chamber and the tube collapses anddroops when a subatmospheric pressure less than a second predeterminedamount is induced inside the suction chamber, thereby providing a clearvisual indication of the pressure inside the suction chamber.